This invention relates to infra-red light emissive devices, and in particular to such devices having active light emissive regions of the ternary solid solution In(Sb, As) and related multicomponent (quaternary or higher) solid solutions.
Light emissive devices have been made that have had an active light emissive region of In(Sb, As) grown epitaxially upon an In As substrate. A problem with this type of construction is that the addition of In Sb to In As to form a solid solution has the effect of changing the lattice spacing. Therefore a graded interlayer was necessary between the active region and the substrate, but even this did not entirely remove the strain from the active region which was relatively heavily dislocated. The present invention is directed to the problem of lattice mismatch.